


Prove It

by sinssansguilt



Category: Undertale (Video Game)
Genre: "Pet" as nickname but not petplay, BDSM, Begging, Biting, Bondage, Dirty Talk, Dom!Sans, Established Relationship, F/M, Female Reader, Fingering, Hair Pulling, One-Shot, Reader falls into Underground, Rough Sex, Second Person, Sensitive bones, Smut, Topping from below, curse words, ectopenis
Language: English
Status: Completed
Published: 2016-04-24
Updated: 2016-04-24
Packaged: 2018-06-04 04:21:18
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 2,547
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/6641260
Author URL: https://archiveofourown.org/users/sinssansguilt/pseuds/sinssansguilt
Summary: <blockquote class="userstuff">
              <p>Your boyfriend accidentally tickles you when he nuzzled your neck and he's feeling a little bit rejected by it. Whatever shall you do?</p>
            </blockquote>





	Prove It

“Have I ever told you how goddamn cute you are?” Sans eyes you intensely, a wolfish grin on his face.

“I could always stand to hear it more often. But not during the show, shhh!” You wave your hands at him, a grin playing on your face. Snuggled up together on the couch at his place, the two of you are spending a peaceful afternoon watching more of Mettaton’s show. You didn’t understand how the monsters here could stand seeing the same show all the time, but you supposed there weren’t many other shows available this far underground. Sans has his arm around your shoulders, something that wasn’t always comfortable for you with his skeletal structure, but his sweater helps cushion you somewhat.

He’s still giving you that look.

“Are you sure the show is more interesting right now?” Using the arm around your shoulder to pull you closer, he begins to nuzzle your neck with his mouth.

You really had been interested in what the answers on the show were and, with your attention split, you weren’t fully expecting neck nuzzles. You burst into uncontrollable giggling. For some reason, his mouth just tickled you instead of titillating you.

Sans stops moving for a moment, then lets go. Still giggling, you see his face has fallen somewhat and feel a little bad. Trying unsuccessfully to wipe the smile off your face, you explain, “Sorry, babe, it tickled!”

He faces towards the screen again, crossing his arms. Was he sulking?

“Hmph. It’s one thing if you laugh when I’m cracking jokes, but I didn’t think I was that bad at touching you,” he grumbles. Oh dear. He took that a little personally, you realize. Crestfallen, you put a hand on his arm.

“Sans, babe, I wasn’t laughing at you! You just tickled me, that’s all,” you insist, squeezing his arm to try to show your sincerity. He pouts for a moment before replying.

“Well, the moment’s passed, I guess. I doubt you’re still interested.”

“Psht, of course I’m still interested! Rude.” You frown disapprovingly at him. Doubting your interest! Pah. The white lights of his eyes swing over to you. There was that hungry look again.

“Prove it.” That wasn’t him sulking. That wasn’t a wounded tone. That was his voice going low and deep to give you a command. An order. You haven’t moved yet, your breathing slower and your eyes wide. He doesn’t make a move, just stares at you, waiting.

You slowly put your hand on his shoulder, unsure what to do at first. Usually, he took the lead. Well, he still felt like he was in charge right now. But.

Pushing his shoulder to turn him towards you, you push down any doubts with it. The corner of his mouth quirks up and he smirks at you, complying. Shuffling around slightly in your seat, you begin to push both his shoulders, whispering, “Down.”

“Who said you could give orders like that?” His smirk contradicts his comment, however, as he allows you to push him into laying down on the couch. You awkwardly scramble atop him, straddling his hips. His hands land comfortably on your thighs as he stares up at you with that damn smirk on his face and that look in his eyes.

You lean down, placing your hands on his chest to steady yourself, and begin to lick at his neck. He jolts slightly, exhaling happily.

“Mm, that’s right, baby,” Sans purrs into your ear. His hands slide up to your back, holding you gently as you lick up to his jaw. He seems to like this, you note, but isn’t reacting much. Moving down, you pull the collar of his sweater and shirt down further to give you access to his collarbone. You slowly lick across it, causing him to moan and jerk his hips a little. A small victory.

Energized by his reaction, your hands scramble down to the bottom of his sweater. Trying to reach between your body, his body, and his clothes was driving you up the wall.

His spine was just begging to be touched and all these damn layers were getting in the way. You sit up abruptly and pull at him, trying to ignore the raised brow and shit-eating grin he gives you.

“Up, up, let me—“

He sits up and you immediately start pulling his shirt and sweater off together, throwing them away from the couch without a thought. You wanted him to make more of those sounds for you.

“Getting a little frantic, babe?” he chuckles, placing his hands back on your thighs. You wanted him to touch you more. With some noticeable amount of desperation, you wrap your arms around him, pulling him close. One hand trails his spine, the other traces along the top of his hip bones jutting out of his shorts. His sharp intake of breath and delicious shudder are intoxicating.

“Down.” You’re more firm this time, pushing him down harder. He lets you maneuver him down again. He’s breathing harder now, staring up at you with hooded eyes. His left eye is starting to glow blue. You feel his erection begin to take form under your hips. Bracing yourself with one hand on the back of the couch, you grind your hips down onto him, whimpering, wanting him inside of you.

“Oh shit,” he breathes, his fingers digging into your thighs as he rolls his hips. You run your fingers along his ribcage, almost musically. He groans deeply, staring at you. Shifting down his body slightly, you bend down and slowly, making sure he was watching you, _slowly_ licked up his spine. His head kicks back as he gasps. You suck on his spine a little.

“Fuck!” He snaps, unable to take more. Sitting up quickly, he grabs your hair and drags you up with him. You gasp at the pain and his tongue pushes into your mouth, one hand still fisted in your hair, the other squeezing your ass. His tongue in your mouth was always overwhelming; it moved differently from a normal human tongue, faster, fuller. He pulls away to breathe, his eyes boring into your own. You’re trembling slightly, panting, still reeling from the kiss. His blue eye is glowing fiercely.

“Get under me, now,” he commands, his voice so deep you almost don’t understand him. He lets go of your hair and, for a moment, you awkwardly shuffle off his lap and try to figure out how to lay down under him. With a flash from his blue eye, he gestures upward with one hand. You levitate off the couch, held up by his magic. This always gave you chills in the best way.

“I thought I told you to get under me,” he snarls, standing up.

“Yes, sir,” you reply meekly. You’re nearly slammed down onto the couch. Hard enough to startle you, not enough to hurt. In a flash, Sans is on top of you, pinning your wrists above your head.

“You know what happens when you don’t follow orders, pet.” His mouth is almost touching yours, his eyes burning through you.

“Yes, sir.” You’re shaking with anticipation. He bites your neck, _hard_. Screeching, your body torques off the couch, pressing against him. Releasing your neck, he licks across what you know will probably bruise by tomorrow. You collapse onto the couch, panting.

“Naughty pets get punished,” Sans whispers, relishing the thought.

“I’m sorry,” you mumble blearily.

“You _better_ be sorry,” he chuckles, gently pulling you up to remove your shirt and bra. He nearly throws you back down to ravish your breasts with his tongue. You grip the fabric of the couch, squirming. Like a good pet. Using his hands to hold your shoulder and your hips down, he teases your nipple with his tongue. Barely licking it. You whine, trying to hold yourself steady to earn his good favor.

“What does pet want?” His voice is like a lifeline and you latch onto it, begging.

“P-please, master, I want—I want you to bite me, hurt me, your cock inside me, please, oh god,” you whimper, your voice strained from desperation. Sans bites your nipple hard, causing you to shriek and thrash underneath him. He releases your sore nipple, laughing darkly to himself.

“I have such a dirty little fucktoy, don’t I?” He shifts back far enough to slide your pants off. You obediently rest your feet on his shoulders, breathing heavily, aching for more.

“Well, look at this,” Sans drawls, rubbing a finger against your soaked underwear. “Already this wet for me? Did you enjoy touching me that much?” His grin is like a wolf’s, his gaze trained on your face.

“Yes, sir. I really like the sounds you make…” you offer hesitantly, uncertain if he wanted that much detail. On one hand, you could be rewarded for a good answer. On the other hand, you could be punished for offering more than was requested. Both options fill you with yearning.

“Is that so, dear?” he mumbles, almost to himself, as he pulls your underwear off, tossing them away.

“Yes.”

“I think pet’s sounds are much, much more interesting to listen to.” He lays your legs back down and climbs atop you again, straddling you. Rubbing a thumb over the nipple he had ignored up until now, he presses two fingers into your mouth. You lick them, just about drooling to get at them. Licking, sucking, tasting them, you stare up at Sans the entire time, making small noises for him. His face is flushed, the glow of his eye even brighter. Yanking his fingers out of your mouth, he removes his other hand from your breast, bracing it on the couch beneath you.

“Make more of those noises for me,” he commands silkily, pressing the two fingers you sucked inside of you.

“Aaah! Oh god!” you cry out, your hands digging into the armrest just behind your head. His fingers angled upward slightly, pounding in and out of you, right into the perfect spot that always reduced you to a quivering puddle. He watched your face intently, his mouth slack and smiling, clearly enjoying the show you’re giving him. He grinds his fingers against the exact spot you like, causing you to nearly scream from pleasure.

“Oh yeah, pet, just like that. My little fucktoy loves to make such a delicious display for me,” he murmurs, switching back to thrusting his fingers in and out. This was destroying you, you were so close.

“Please! Please, Sans, please!” you scream frantically, arms trembling from holding onto the armrest so tightly.

“‘Please’ what, pet?” he asks, mocking you.

“Cum, please let me cum! Please, oh god, please, I need it, I need it, I-I-I—“

“Cum for me,” he commands, biting into your neck just after finishing his sentence. Your entire body locks up, you stop seeing anything, you choke on your own breath for a moment. His fingers inside of you prolong the orgasm; you start to feel lightheaded but never want it to end. Finally, you collapse, your entire body going slack beneath him.  
He lets go of your neck and slowly pulls his fingers out, smiling down at you with that hungry look still. You make little happy noises without intending to, your whole body reeling from that orgasm.

“Th—. Thank you…” you mumble woozily, enjoying the aftereffects. Sans pets your hair for a moment, gazing down at you as you recover some lucidity.

“You’ve been very good so far. Ready for my cock?” he inquires sweetly. You nod, smiling up at him, probably looking slightly goofy. You’re too blissed out to care.

“Good pet.” He stands up briefly, pulling his shorts off and tossing them aside. You stare at his cock, summoned with his blue magic expressly for both of you to enjoy. He climbs back onto the couch, pulling your legs apart and settling between them. Grabbing his cock, he presses against you, trying to push into you at the right angle. You tilt your hips, trying to make it happen faster. There…!

His thick cock slides slowly, ever so slowly inside of you. He places both hands by your head, looming over you slightly. He’s biting his lip, his eyes closed. Savoring. You whimper, wriggling your hips a little, desperate for friction.

“We move at _my_ pace,” he growls, opening his eyes to glare you down. You settle briefly, your whining becoming more needy.

“Please…” you beg pathetically. He slowly begins to thrust in and out, as slowly as he can manage. You moan for him, hoping for more. Bending down to come flush with your body, he licks the edge of your ear, causing you to jolt.

“Such a good fucktoy, always so _wet_ and _warm_ for me…” he whispers into your ear. Shivering, you dig your hands into the couch again, trying to behave as you begin to moan in earnest.

Sans starts pounding into you suddenly, making you cry out. He bites your earlobe, thrusting faster and faster. You’re screaming, begging. Your head is being pushed into the armrest. You’re just about thrashing beneath him, it feels so good. He releases your earlobe and twists your nipple, hard.

“Cum,” he orders once again and your body tenses up on command. Practice has made perfect as your body clenches up with a powerful orgasm. Finally you let go and crumple beneath Sans, panting hard, murmuring your gratitude and praise.  
His cock still stiff, he releases your nipple and slams into you. His thrusts are shorter, his voice hitches in his throat, he’s almost drooling over you.

“Fill me up,” you encourage him huskily, “fill up pet with all of your magic, mark me as yours, cum inside of me…!”

“Fffuuck!” he curses once, thrusting one last time to freeze over you as you feel his cock pump into you. You love watching his face as he orgasms. His eyes closed, he bites his lip, he trembles ever-so-slightly, his voice keens a little. And then he’s spent and he collapses on top of you with a shudder.  
The blue fire in his eye extinguishes and his cock and the mess he made vanish with it. The two of you simply lay for a few moments, breathing deeply. You pry your fingers off of the couch’s fabric, flexing the stiffness out of them.

“That. That was amazing, babe. Oh my god,” you mumble contentedly.

“Fuck, you were so hot on top of me,” he exhales, turning his head to look at you with a weak smile, “we have to do that more often.”

“Oh god, yes,” you agree. Slowly, he gets off of you, remembering that he’s basically poking you in the stomach with his ribcage. Leaning on the far armrest, he grins dreamily at you. You sit up and glance around.

“Where did my underwear go?”

“Hm? Oh, I don’t know.”

“You’re the one who took them off,” you retort with fake sourness. He giggles and shrugs at you. You don’t feel like getting up from the couch, though, so you drag the throw blanket off the back of the couch and wrap yourself up in it, snuggling up against Sans. You’ve missed the entire show. That’s fine. It’ll be on again soon enough.


End file.
